Method and apparatus for subjecting material to conditioning gas with whirling motion



Dec. 31, 1968 R. E. FUTER 3,418,724

METHOD AND APPARATUS FOR SUBJECTING MATERIAL Sheet TO CONDITIONING GASWITH WHIRLING MOTION Filed Oct. 11, 1967 Dec. 31, 1968 R. E. FUTER3,418,724

METHOD AND APPARATUS FOR SUBJECTING MATERIAL Sheet TO CONDITIONING GASWITH WHIRLING MOTION Filed Oct. 11, 1967 Dec. 31, 1968 R. E. FUTER3,418,724

METHOD AND APPARATUS FOR SUBJECTING MATERIAL TO CONDITIONING GAS WITHWHIRLING MOTION File'd Oct. 11, 1967 mdE United States Patent 3,418,724METHOD AND APPARATUS FOR SUBJECTING MATERIAL TO CONDITIONING GAS WITHWHIRLING MOTION Rudolph E. Futer, Oakland, Calif., assignor to BangorPunta Operations, Inc., Oakland, Calif., a corporation of New YorkContinuation-impart of application Ser. No. 486,965, Sept. 13, 1965.This application Oct. 11, 1967, Ser. No. 687,406

22 Claims. (Cl. 34--10) ABSTRACT OF THE DISCLOSURE Small objects,particles or liquid, are subjected to a conditioning gas, e.g., to heator cool them or, in the case of solids, to change their humidity, bysupplying them to a whirl chamber defined by a confining wall at least apart of which is a membrane wall having a plurality of gas passagesdirected to emit a series of gas jets spaced apart in thecircumferential direction by less than the throw distance of one gas jetto form a high-velocity gas current which moves peripherally about thechamber wall and entrains the material being treated, moving thematerial adjacently to said wall. The chamber may be one of a series ofpassive housings which are moved along a stationary membrane Wallconstituting the active part of each chamber; or the apertured membranewall may be a fixed part of the chamber. In either case, the material issubjected to repeated blasts from the gas jets during each circuit, and,in the embodiments shown, many circuits are made about the chamber wall.

This is a continuation-in-part of my application Ser. No. 486,965, filedSept. 13, 1965, now abandoned.

The invention relates to a method and apparatus for changing thecondition of material by the action of a conditioning gas which is inrapid whirling motion and entrains the said material, the term conditionbeing used herein, for brevity, to include temperature and/or humidityof or concentration. The invention is applicable to treating particlessuch as grain, sawdust, cement, nuts, berries, plastic nibs and powderedmaterial, or liquid, such as milk or chemical solutions or mixtures; theconditioning gas may be air, either untreated, dehydrated, or containingmoisture vapor or droplets, e.g., in a controlled concentration, and maybe heated or cooled, or may be any other gas, such as nitrogen, carbondioxide or methane, either pure or containing vapors of a liquid to beabsorbed or emitted by the material undergoing treatment.

The invention can be used, for example, to chill or freeze vegetables orfruits, such as berries, or for heating materials such as plastic nibsor powder, or comminuted metal, before the material is fed to a furnace,extruder or other treating unit. Other uses are to dry or humidity thematerial to a desired moisture content and to heat, cool or concentrateliquid to any desired degree. The term moisture is used broadly hereinto include water and non-aqueous liquids that may occur in or beabsorbed by the material being treated, or occurring in or constitutingin vaporized form the conditioning gas.

The rapidity of the change in condition of such material by contact witha conditioning gas depends largely ice on the relative velocity betweenthe gas and the material (whereby the boundary layer or film of gasenclosing the solid or liquid material is destroyed or fresh surfacesare created in a liquid), upon the difierence between the properties ofthe gas (e.g., its temperature and/or humidity) and the properties ofgas in equilibrium with the material in its desired ultimate condition,and upon the separation between the individual drops or objectsundergoing treatment as well as the tumbling motions of solid objects,the last being often important to expose all sides to the gas. Further,the material must be subjected to the gas for a residence timesufiicient to effect the desired change in condition.

It is desirable that all parts of the material be subjected to theconditioning gas for approximately the same residence times, both toeconomize on the size of the equipment and the expenditure of power tocompress the conditioning gas and to avoid excessively long exposure ofsome of the material to the gas, which can result in a non-uniformchange in conditions and may, in some situations, alter othercharacteristics and damage portions of the material by over-exposure tothe gas.

Further, it is important in such treatments to engage the material withthe conditioning gas in such a way as to promote a rapid equilibriumbetween the gas and the material. This involves insuring that there is ahigh relative velocity between them.

Prior methods and apparatus for subjecting small or subdivided materialto the action of a conditioning gas have been deficient as to one ormore of the abovementioned desirable features. In particular, those thatcarried objects by a conveyor through an enclosure containing eitherstill or moving gas did not continually disrupt the boundary layer. Onthe other hand, those that entrained the material in a current of gasflowing through a duct or about a whirl chamber or cyclone werewastefill of the conditioning gas, leading to excessive compressioncosts, and attained only a slow change in the condition of the materialbecause: (1) they employed the principle of concurrent flow in which thematerial was merely carried by a gas current and the gas had, throughoutmost or all of the residence time, a low velocity relative to thematerial; and (2) they did not retain the individual units of thematerial in contact with the conditioning gas for equal residence times.Also, prior apparatus often conducted the conditioning gas into thetreating enclosure in a manner leading to turbulence, thereby causingenergy loss.

Now according to this invention, it was found that material such assmall solid objects or particles or liquid can be effectively subjectedto the action of a conditioning gas with improved results by admittingthe gas into a whirl chamber having a confining wall as a series ofclosely spaced gas jets which cooperate to form a gas current movingperipherally about the chamber, and admitting the material into thewhirl chamber for entrainment by said gas current, the velocity of thecurrent being sufiiciently high to cause the material to move adjacentlyto the chamber wall, whereby the units of the material are subjected ineach of one or more circuits about the chamber to blasts from severalsuccessive gas jets. These jets emanate from locations on the confiningwall that are spaced apart in the circumferential flow direction of thegas current by distances less than the throw distance of one jet andhave their major flow components in a common circumferential direction(which need not be along a true circle but may be skewed to follow ahelical path within the chamber), the said locations being such that atleast one jet emanates beneath another gas jet that is still in being.Preferably, jets are emitted from at least three and, in mostembodiments, from a larger number, such as ten or more, passages throughthe chamber wall situated at the stated small spacings.

As a gas jet moves outwardly from its origin its gas diffuses laterallyand its forward momentum decreases. At a certain distance from theorigin, herein called the throw distance, the jet can be deemed to bedissipated and no longer in being. For the purposes of the presentspecification, a gas jet is considered to be in being when its velocitypressure in the jet direction, after moving through otherwise still air,is at least of its original velocity pressure, e.g., as measured by apitot tube pointed in the upstream direction, all pressures beingrelative to the static pressure of the air immediately outside of thejet.

The consequence of providing such a plurality of successive gas jetswhich are spaced and positioned to cooperate with one another is that amore useful gas current is formed than can be formed by a single gasjet, given the same total gas flow rate and pressure of the gas supplyand the same angular inclinations of the gas jets to the local surfaceof the confining wall. This combination of closely spaced jets producesa gas current that is similar to a sheet of gas, which current flows atincreased velocity along the confining wall. Such increased velocity isdesirable to insure that the entrained objects or liquid dispersed asdrops move adjacently to said wall, being urged to that path bycentrifugal force. The effect of such closely spaced gas jets isdescribed in detail and illustrated by graphs based on experimental datain my US. Patent No. 3,267,585, and the disclosure thereof isincorporated herein by reference. In brief, it is shown therein that thevelocity component parallel to an apertured wall of a single gas jetemitted from the wall at a small angle to that wall is considerably lessthan the jet velocity (measured in its flow direction); and that asuccession of such gas jets, spaced apart by distances less than thethrow distance of one jet, causes a progressive increase in the velocitycomponent parallel to the wall surface of the total gas current whichresults. The maximum velocity is attained beyond the third jet of theseries. It may be that the jet emanating from each gas passage (save theone most upstream) is deflected toward the apertured wall by a jet froma more upstream location which is still in being, thereby causing eachdownstream jet to move more nearly parallel to the wall surface;however, no theory of the nature of this cooperative effect is hereinrelied upon.

By thus moving the material, entrained in the gas current, adjacently tothe confining wall past the successive apertures in the confining wall,the material is subjected repeatedly to high-velocity gas jets in asingle circuit about the chamber. Such a succession of jets produces amore rapid change in the condition of the material than would occur ifthe material were merely carried about the whirl chamber in a gascurrent of the same total quantity and the material were not subjectedto such a succession of blasts. The subdivided material is, further,tumbled while passing the successive gas blasts.

According to another feature of the invention, the residence time of thematerial is controlled and made uniform among the portions thereof. Twoalternative expedients are preferred: In one, a quantity of thematerial, e.g., a group of objects, is charged at one time into a whirlchamber, whirled therein by the treating gas for a selected period, anddischarged at one time. For example, there can be a succession ofhousings, each forming a passive part of a whirl chamber, which aremoved along a table provided with apertures and forming the active partsof said chambers. In the other expedient, the material is chargedcontinuously and moved along a helical path for several circuits withina whirl chamber and discharged continuously; because all portions of thematerial follow more or less the same helical path, they make about thesame number of circuits and are, hence given substantially equalresidence times.

At least a part of the confining wall of the whirl chamber is formed ofa membrane wall having a series of closely spaced apertures or gaspassages extending therethrough, said membrane wall being the activepart of the whirl chamber and forming a wall of a plenum chamber whichis situated outside of the whirl chamber and to which the conditioninggas is supplied under pressure.

In one embodiment, the said membrane wall is a longitudinally elongatedtable and the passages emit jets making angles less than 35 to thesurface of the membrane wall and all flow in about the same direction,such as longitudinally. The device includes a plurality of whirlchambers, each formed in part by the said active membrane wall and inpart by an independent passive housing, each housing having a confiningwall that extends through an are more than half and less than a fullcircle and leaving an opening. The several housings are moved along themembrane wall with the opening-s thereof juxtaposed to the membranewall, and the width of the opening (in the circumferential direction) isgreater than the interval between gas passages, so that at least twoand, preferably, more gas passages are at all time opposite the opening.Thereby progressively changing groups of jets cooperate to form a gascurrent which carries about each whirl chamber the objects which wereintroduced through the said opening. Each housing may have its confiningwall imperforate and an opening at each end, displaced radially inwardsfrom said wall, for the escape of gas in a substantially axialdirection. However, the confining wall may, in certain embodiments, havesmall passages to permit gas to escape.

Although the arcuate extent of the passive housings was, for simplicity,stated as a fractional part of the arc of a circle, it will beunderstood that this does not imply that the whirl chamber is trulycylindrical; it may take any desired shape, such as elliptical, or mayhave a varying radius, e.g., decreasing in the direction of gas flow, orcan even consist in part or entirely of successive fiat secr tions,whereby its cross section is polygonal. Usually the whirl chamber has aconstant cross section along its central axis; however, this is not inevery case essential, and the cross section of the whirl chamber may,for example, be smaller at one end than at the other end.

In another embodiment, the whirl chamber consists of relativelyimmovable parts, the confining wall about the central axis including orconsisting of the active membrane wall which is advantageously inwardlyconcave about said axis. For example, the chamber wall may be shaped asa cylinder or as some other surface of revolution about said axis.Again, the passages are formed to emit gas jets which make anglespreferably less than 35 to the local part of the membrane wall, in acommon circumferential or slightly helical direction. The activemembrane portion may occupy any desired fractional part of the confiningwall, up to but it conveniently extends through only a partial sector,usually between 20 and e.g., 90, about the said axis, beingadvantageously situated at the bottom of the chamber to facilitateplacement of the plenum chamber beneath the whirl chamber. The membranewall is provided at least at the inlet end, so that the admittedmaterial is immediately entrained by a gas current; it may extend fullyor partially to the outlet through which the material is discharged. Thematerial, after admission through the inlet near one end of the whirlchamber, makes several peripheral circuits along a helical ornear-helical path before reaching the outlet near the other end. Theresidence time can be varied by altering the inclination of the centralaxis (which alters the pitch of the helical path) and can be altered bychanging the spacing between the inlet and outlet, or by regulating thespeed and direction of the gas current.

In all embodiments, the passages through the membrane wall may be formedas is described in my U.S. Patent No. 3,131,974, and may be elongatedslits placed in one or more rows. However, passages of otherconfigurations can also be used. It is desirable to form the passages bybending portions of the membrane wall outwardly into the plenum chamber,so that the surface of the membrane wall which is toward the interior ofthe whirl chamber is unobstructed to the movement of gas and saidmaterial adjacently to the membrane wall.

In all embodiments, fresh conditioning gas is admitted into the whirlchamber throughout substantially all of the period of residence of thematerial therein, thereby causing: (1) a continued high-velocity gascurrent throughout all or most of the residence period, whereby thematerial continues to move adjacently to the confining wall and isrepeatedly subjected to blasts from the gas jets, and (2) an increase inthe rate of change in the condition of the material, in that otherwisethe temperature and/or the humidity of the gas would approach thecondition in equilibrium with the material, leading to a decreased rateof change.

Having indicated the general nature of the invention, reference is madeto the accompanying drawings forming a part of this specification andshowing certain preferred embodiments, wherein:

FIGURE 1 is an elevation of one embodiment, parts appearing in section;

FIGURE 2 is a fragmentary plan of the parts of FIG- URE l beneath thefeeder;

FIGURE 3 is a fragmentary plan of the housing in the lower course ofFIGURE 1, parts being broken away to show the membrane wall;

FIGURE 4 is a fragmentary longitudinal sectional view through apreferred form of the membrane wall, on an enlarged scale;

FIGURE 5 is a fragmentary longitudinal section, on an enlarged scale, ofthe front end of the same apparatus, parts appearing in elevation, and amodified form of the feed device being shown schematically;

FIGURE 6 is a perspective view of a housing, showing a modifiedembodiment wherein the gas escapes through small openings in theconfining wall of the passive housing;

FIGURE 7 is a longitudinal section through the membrane wall and onemovable whirl chamber, showing another modification;

FIGURE 8 is an elevation of a further modified embodiment, wherein allparts of the whirl chamber are stationary relatively to each other,parts being broken away; FIGURE 9 is a transverse section showing theoutlet, taken on the line 9-9 of FIGURE 8;

FIGURE 10 is a transverse sectional view showing the inlet taken on theline 1010 of FIGURE 8; and

FIGURE 11 is an elevation of another modified embodiment, similar to thedevice shown in FIGURE 8.

Referring to FIGURES 1-5, the first embodiment includes, as itsprincipal components; a plenum chamber of 10 which is supplied with gasunder pressure through a supply duct 11; a longitudinally elongatedactive membrane wall 12 which forms the upper bounding wall of saidplenum chamber and has extending therethrough a multitude of gaspassages, e.g., formed by transverse slits 13 situated at closelongitudinal intervals throughout all or most of its length; a pluralityof passive whirl chamber housings '14, each being substantiallytrough-shaped and provided with end walls 15, 16, the said housingshaving openings 17 extending through their full lengths (transversely tosaid membrane wall); conveyor means, such as a pair of endless chains18, situated one at each end of the housings; inlet means for theobjects, such as a feed hopper 19 which is situated to supply theobjects for flow by gravity into the housings through the openings 17when the latter are upwardly directed; and outlet means such as areceiving hopper 20 situated at the rear end of the membrane wall.

A gas of any desired composition, such as cold air, is supplied to theduct 11 from a suitable source, such as a blower 21, which gas may passthrough a temperatureand/or humidity-conditioning means, represented bya heat exchanger 22. The latter, if a cooler, may include a cooling coilthrough which a refrigerant is circulated via pipes 23 and 24.

The plenum chamber is closed at the bottom, sides and ends, save for itscommunication with the supply duct 11, and gas under pressure issupplied from this chamber to the several passages 13. These passagesare inclined upwardly in a common longitudinal direction as shown inFIGURE 4, e.g., toward the discharge end (adjacent to the hopper 20) asshown, or, if desired, in the opposite longitudinal direction.Preferably the wall 12 is shaped to lie in straight longitudinal lines;its trans verse section may be similarly situated in straight lines,wherebe the said surface is flat; however, these are not absoluterequirements, and other geometric shapes may be used for the saidsurface. The said surface is preferably free from obstructions and islongitudinally continuous, save for the depressed portions 25 that formthe passages 13. These depressed portions have upstream edges 26 thatunderlie the downstream edges 27 of the continuous membrane wall bysmall gaps, such as 0.7 to 2.5 millimeters, when the passages are spacedlongitudinally by distances such as 1.5 to eight centimeters. Thereby aplurality of passages 13 cooperate to form a gas sheet moving in alongitudinal direction with high veloc- 1ty. Advantageously, the edge 27do not overlap the edges 26, thereby achieving a minimum pressure lossin the gas and reducing the tendency for the accumulation of lint anddust between these edges.

The passages 13 may be formed as one or more rows of transverselyelongated slits, having lengths many times the slit height, e.g., twolongitudinal rows A and B as shown, with the slits of adjacent rows.This promotes the formation of a sheet of gas of uniform velocity andmass flow of gas, having a high velocity component parallel to themembrane wall surface for a given total flow of gas and gas supplypressure.

The housings 14 are secured to the conveyor chain 18 by pins 28 that arefixed to the end walls 15 and 16 of the housings and pivotally movable,either relatively to said end walls or to the chain. These pins arepreferably situated eccentrically relatively to the center of gravity ofeach housing toward the opening 17, as shown, so that these openings areupwardly directed when moving 1n the upper course, away from themembrane wall 12. These pins may be located at various geometriclocations. For example, in the embodiment shown, in which each housing14 has the cross sectional shape of the segment of a circle extendingthrough about 315, they may be situated at the axis of revolution ofsaid housings. When one or both of the end walls 15, 16, has a gasoutlet opening 29 situated at said axis, the pins are mounted by openspiders 30 secured to the end walls, leaving the openings 29 free forthe escape of gas. The chains 18 extend about an idler sprocket 31 and adrive sprocket 32 that is driven by suitable means, such as avariable-speed electric motor (not shown). A suitable number of supportidler sprockets or boggies 33 are provided to support the chain 18 and,there-by, the housings 14 when in their upper course.

The chains 18 and the sprockets 31 and 32 are situated to cause thehousings 14, when in their lower traverse or course, to move in closejuxtaposition, e.g., in sliding relation, to the upper surface of themembrane wall 12. To this end each housing 14 may be formed with aconfining wall, e.g., of sheet metal, extending arcuately about a circlethrough an arc of about between 270 and 330, and formed at least at oneend with a flange 34 that lies parallel to the surface of the wall 12 inclose relation,

e.g., in sliding engagement, therewith. The widths of the flanges 34 arepreferably such that the adjacent housings are interconnected, as far asis practicable, by said flanges, to cover the outlet ends of allpassages 13 that are not situated opposite the openings 17, as shown inFIGURE 5. The edge 35 of each housing away from the flange 34 may beenlarged and convex for sliding engagement with the membrane wall.However, other arrangements for preventing the flow of gas todestinations other than the housings, e.g., webs joining the housings,may be employed. This close juxtaposition of each flange to a part ofthe next housing (or provision of a web) minimizes the spillage of thesmall objects into gaps between adjacent housings when supplied from thefeed hopper 19 and reduces waste of compressed gas from the plenumchamber. The lateral overall extent of the slits 13 is slightly lessthan the lengths of the housings 14, thereby avoiding waste of gas.

To cause the housings when in their upper course to assume positionswith their openings 17 uppermost, it is necessary that provision bemade, either by providing positioning means (not shown) or by locatingthe pins 28 toward the openings 17 from the centers of gravity of thehousings. In the embodiment shown, this is effected by providing weights36, thereby permitting the pins to be situated at the central axes ofrevolutions of the housings and of the openings 29.

The apparatus further includes a concave containing wall 37, mounted instationary relation to the wall 12 and situated at the upstream endthereof, near the sprocket 32, and disposed to engage the flanges 34 andedges 35 of the housings during movement from their upper to their lowercourses. The wall 37 assists in the inversion of the troughs and, bycontact of the edges 35 thereof, prevents spillage of the objects fromthe housings during this inversion. To insure continuous contact of theedges 35, the wall 37 is smoothly joined to the wall 12, which has a dip12a. The gas sweeps the dip to prevent accumulation of objects therein.Flanges 37a prevent lateral spillage.

The whirl chambers defined by the housings 14, the parts of the membranewall 12 opposite the openings 17, and the end walls and 16, are providedwith means for outflow of gas without the said objects. In theembodiment being described, at least one end wall and, preferably, bothend walls are provided with the opening(s) 29, previously mentioned,situated at or near the central axis of the whirl chamber and having adiameter smaller than that of whirl chamber. Because the objectsentrained by the gas current move circumferentially in close proximityto the outer confining walls 12 and 14, they are not present in the eyeof the gas vortex and only gas escapes through the opening(s) 29 insubstantially axial directions. The pressure within the central part ofeach whirl chamber is thereby maintained closely to the ambientatmospheric pressure outside of the chambers. It will be understood thatwhen the gas has a composition making it undesirable to vent it to theatmosphere, the entire apparatus is enclosed in a suitable hood (notshown) for collecting the discharged gas.

In a modified arrangement, shown in FIGURE 6, the end walls 15, 16 ofthe housings 14' may be imperforate, and the gas is discharged throughsmall apertures having sizes small enough to retain the objects. In thisembodiment, the sections containing the apertures 38 are shaped toconform to the curvature of the housing, where the apertures 38 can belocalized in a limited zone of the housing. This zone is preferablysituated in the parts of the housings in which the gas current flowsdownwardly. (In FIGURE 6 it is assumed that the gas current has aclockwise whirl direction, indicated by the arrow W, which requires themembrane wall slits to be upwardly inclined toward the front, as shownin the next embodiment.) It will be understood that the apertures 38 aremerely illustrative, and that other openings may be provided; thus, theapertures 38 may be formed by woven wire screens. A flange 34 and heavyedge 35 may be provided, as described above for the parts 34 and 35.

In another modified arrangement, shown in FIGURE 7, the cross sectionalcontour of each housing is not arcuate but is, nevertheless concave. Asillustrated, the passages 13 in the membrane wall 12 are, in thisembodiment, directed toward the feed end (i.e., toward the left, asviewed in FIGURE 1), and the housings 14" are formed so that eachincludes a section 39 which is joined to a flat flange 34" and has acurvature of diminishing radius in the direction of peripheral gas flow.The section 39 is joined to a plurality of flat segments 40, eachangularly related to the others, to form, in cross section, a part of apolygon. The last of these segments is joined to a flange 35", of lengthto extend closely to the flange 34 of the adjoining housing 14" (notshown). (This replaces the thickened rubbing edge 35 previouslydescribed.) It is evident that a complete housing can be formed of onlythe sections 39 or only the sections 40, and the inclusion of bothgeometric forms in a single housing is illustrated principally toexemplify various embodiments of the invention. The overall crosssection of the housing shown in this view is oblong, with the major axisinclined to the membrane wall upwardly in the direction of the gas sheetflow, in the direction shown by the arrow W". This results in a gradualdeflection of the gas sheet.

Reverting to FIGURE 5, a specific means for preventing spillage of theobjects being supplied to the troughs is indicated schematically. Thefeed hopper 19 is provided with a vibratory trough 42, actuated by amotor 43 mounted on a fixed support (not shown) and an actuating arm 44,that moves the trough vertically and longitudinally, e.g., through aclockwise circular path. The objects are discharged from the end of thetrough only when the trough is vibrated by the motor 43. The motor isenergized by a suitable electrical circuit (not shown) only when theopening 17 of a housing 14 is beneath the discharge end of the trough.For example, the energization of the motor can be controlled by amicro-switch 45 that is closed by cam surfaces 46 fixed to the shaft 47that drives the sprocket 32. The vibratory feeder, being not a part ofthe invention and being well known per se, is not further describedherein. It will be understood that one can use any other suitable meansfor feeding objects in coordination with the passage of the troughs andinterrupting feeding when the openings 17 are not beneath the feeddevice, and that such a control is not always necessary, as when thegaps between the adjacent housings or their flanges are smaller than theminimum diameters of the objects, or when connecting webs are providedbetween successive housings. Similarly, various arrangements other thanthat shown are possible to prevent spillage of the objects from thehousings while moving within the curved wall 37; the specificarrangement selected will depend upon the nature and sizes of theobjects. Hopper 20 may feed a belt 41.

In operation, the objects to be treated by the gas are supplied to thehousings 14, 14 or 14" as they move under the discharge of the feeddevice 19 or its chute 42. As each successive housing moves adjacentlyto the curved wall 37 it is inverted to bring its opening 17 to thebottom, adjacently to the active membrane wall 12. The edges 35 slide onthe walls 37 and 12 to prevent loss of the objects from the housings.Thence the housings move in close proximity to the membrane wall,preferably in sliding engagement therewith, whereby the flanges 34 closethe upper ends of the passages 13 that do not discharge into theopenings 17. The plurality of longitudinally aligned passages 13 thatdischarge into a common opening 17 cooperate to form a current of gashaving a high velocity parallel to the membrane wall, and the gascurrent is deflected by the confining, passive wall of the housing tomove peripherally within the respective housing in a counterclockwisewhirl direction shown by the arrow W (FIGURE Each said current of gasentrains the objects, causing them to move peripherally many times aboutthe whirl chamber until the respective housing reaches the rear end ofthe membrane wall and the objects wall into the hopper 20. (Movement ofthe gas sheet and objects is clockwise in the case of FIG- URES 6 and7.) During each circuit the objects are subjected repeatedly to blastsof gas as they move past the passages 13. These blasts move more rapidlythan the objects and their repetitive actions promote a rapid change instate.

The speed of the housings may, for example, be such as to provide aresidence time in each housing of from eight seconds to two minutes.

By supplying fresh air all along the membrane rapid changes in theconditions of the objects are insured. It is possible, for example, bysupplying gas at a tempera ture of 75 F. to cool initially hot objectsto about 80 F. although the average temperature of the efliuent gas isconsiderably above 80 F.

According to the embodiment shown in FIGURES 8-10, the membrane wall isfixed to the housing of the whirl chamber and may form all or afractional part thereof. In the specific embodiment shown, the activemembrane wall constitutes only a minor fraction of the enclosing housingwall, e.g., from 20 to 130 about the central axis, and a passive,usually imperforate, wall complements the active wall. Thus, the whirlchamber shown includes a passive confining wall 48, e.g., of cylindricalshape and having a circular cross section, and end walls 49, 50, thatmay be imperforate or have central openings 51. These end walls may beremovable for installation or replacement of a metal liner or wearplate. The active portion of the confining wall is a membrane section 52which is curved in conformity to the wall 48 and is formed with passages53 extending therethrough. These passages may be formed as describedabove for the passages 13, with rows of slits, each row extending in acircumferential direction through the extent of the membrane and theslits in adjacent rows being in overlapping relation, as shown. Aplurality of successive slits, at least three and preferably many more,as shown, is provided in each said row of slits, the successive slits ineach row cooperating to produce a gas sheet having a high velocitycomponent parallel to the inner, circumferential surface of the chamber,in the direction indicated by the arrow D. Gas under pressure issupplied to the outer side of the active membrane section 52 by a supplyduct 54 via a plenum chamber 55 that encloses the active section 52. Thesaid gas may be conditioned as previously noted. The section 52 mayextend through any desired longitudinal extent of the whirl chamber,such as through half or more, up to all of its length, preferablyincluding the inlet end.

A feed hopper 56 is joined to an inlet opening 57 near one end of thechamber wall 49, situated preferably above the lowest part of thechamber, so that objects can be admitted by gravity and be entrained bythe gas sheet formed in the active wall part and deflected peripherallyabout the passive part. The hopper 56 may include suitable means (notshown) such as a continuously driven star feeder, for regulating therate of admission of the objects. At the other end the chamber has anoutlet opening, such as an opening 58 to which is fitted a dischargeduct 59 disposed tangentially to the confining wall.

Optionally, the apparatus is provided with means for adjusting theinclination of the central axis of the whirl chamber relatively to itshorizontal position. These means are indicated schematically by asupport member 60 secured to one end of the housing and pivotedrelatively to a fixed support 61 by a pivot pin 62, and, at the otherend, a vertically adjustable support. Vertical adjustment of the latteris possible by a wedge 63 that acts between a support 64 on the whirlchamber and a stationary support 65, and is movable by a screw 66 thatis rotatable but axially secured to the wedge and in threaded engagementto a stationary plate 67 that is fixed relatively to the support 65.

According to a modified embodiment, shown in FIG- URE 11, the whirlchamber is defined by a frusto-conical wall including a passiveimperforate section 48' and an active membrane wall at its bottom,shaped in conformity to the section 48, and enclosed on its outer sideby a plenum chamber The parts 54, 56', and 58' are as previouslydescribed for the parts 54, 56, and 58. Support means for adjusting theinclination as described for FIG- URES 8-10 may be provided. Thisembodiment provides a whirl chamber of changing, specificallydecreasing, internal diameter, in the helically advancing flowdirection.

The operation of the embodiments according to FIG- URES 8-11 is asfollows: The gas jets emanating from the passages 53 in the activemembrane wall form a gas current that moves at high velocityperipherally about the whirl chamber. The material, whether solid orliquid, admitted through the inlet 57 are entrained by the gas currentand moves circumferentially about the chamber wall. The material isrepeatedly subjected to gas jets during each peripheral circuit, causinga rapid change in its state. Due to the axial progression of the gastoward the outlet end, the material moves in helical paths, ultimatelyreachin the outlet opening 58 or 58' and being discharged therethrough,together with gas. When the openings 51 in the end walls are provided,some of the gas escapes axially. If desired, the gas can be dischargedsubstantially entirely through the opening 51, as by connecting theoutlet 58 or 58' to a device, such as a lock like a star feeder, thatprevents the fiow of gas therethrough.

The residence time of the material within the whirl chambers of FIGURES8-11 depends on the gas velocity and on the number of circumferentialmovements of the material. The latter implies dependency on thetightness of the helical turns of the path followed by the material.This tightness is, in part, influenced by the inclination of the centralaxis of the whirl chamber, which can be adjusted. Thus, moving the wedge63 to raise the inlet end causes the material to move more rapidly inthe axial di rection, thereby widening the helical turns of the path andreducing the residence time.

I claim as my invention:

.1. Method of changing the condition of material by conditioning gaswhich comprises the steps of:

(a) forming within a whirl chamber which has a confining wall a gascurrent which moves peripherally about the chamber adjacently to saidwall by emitting through at least a part of said wall a series of gasjets having major flow components parallel to the local part of the wallin a common circumferential direction, said jets emanating fromlocations which are spaced apart in the flow direction of said currentby distances less than the throw distance of one jet and are positionedso that a jet emerges from said wall under another jet which is still inbeing,

(b) admitting said material to the chamber and moving it as small unitsadjacently to said wall about the chamber by entrainment in said gascurrent, whereby the units are subjected repeatedly to blasts from saidjets during a circuit, and

(c) discharging the material from the chamber.

2. Method as defined in claim 1 wherein said series includes at leastthree jets spaced apart and positioned as defined.

3. Method as defined in claim 1 wherein gas from said current isdischarged from the chamber in a direction substantially parallel to thechamber axis at a location displaced radially inwardly from said wall.

4. Method as defined in claim 1 wherein said units of the material aremoved about said chamber in repeated circuits and are subjectedrepeatedly to jet blasts during each of several circuits.

5. Method as defined in claim 1 wherein said jets are emitted through anelongated membrane wall which constitutes a part of the confiningchamber wall, and the remaining part of the chamber wall extends aboutan arc greater than half and less than a full circle, and is moved alongsaid membrane wall.

6. Method as defined in claim 1 wherein said jets are emitted through apart of the confining chamber wall which part is stationary relativelyto the remaining part of the confining wall.

7. In a device for changing the condition of material by a conditioninggas:

(a) a whirl chamber having a confining wall defined at least in part bya membrane wall having extending therethrough a plurality of gaspassages which are directed to emit a series of gas jets having majorflow components parallel to said membrane wall in a commoncircumferential direction of the chamber, said passages being spacedapart in said circumferential direction by distances less than the throwdistance of one jet and being positioned so that a jet emerges from apassage under another jet that is still in being,

(b) plenum chamber means which are bounded in part by said membranewall, are in communication simultaneously with said plurality ofpassages, and are situated outside the whirl chamber,

(c) means for supplying said gas to the plenum chamber means for flowsimultaneously through said passages into the whirl chamber to formtherein a gas current moving peripherally completely about the chamber,

(d) inlet means for admitting said material to said whirl chamber forsubsequent entrainment as small units by said gas current and movementcompletely about the chamber adjacently to said confining wall, and

(e) outlet means for discharging said gas and material from the whirlchamber.

8. A device as defined in claim 7 wherein said membrane wall includes atleast three gas passages situated in spaced relation as defined alongsaid circumferential direction, each passage being directed to emit agas jet at an angle less than 35 to the surface of the membrane wall,whereby more than two gas jets cooperate to form said gas current.

9. A device as defined in claim 7 wherein said whirl chamber has atleast one end opening at a location displaced radially inwardly fromsaid confining wall for the discharge of gas from the chamber in adirection substantially parallel to the chamber axis.

10. A device as defined in claim 7 wherein said inlet means and outletmeans include at least one opening formed in said confining wall.

11. A device as defined in claim 7 wherein said passages are formed bydepressions in parts of the membrane wall toward the plenum chambermeans and the surface of the membrane wall which is toward the interiorof the whirl chamber is unobstructed to the movement of gas and saidmaterial adjacently to the membrane wall.

12. A device as defined in claim 7 wherein said membrane Wallconstitutes an active part of the whirl chamber, is elongated in alongitudinal direction, and includes a multitude of longitudinallyspaced gas passages, and the remaining part of the whirl chamberconstitutes a passive part of the whirl chamber, extends about an aregreater than half and less than a full circle, provides an opening, andis mounted for movement in said longitudinal direction along saidmembrane wall with the said opening directed toward the membrane wall,whereby different groups of said pasages emit gas jets through saidopening into the whirl chamber when said passive part is movedlongitudinally.

13. A device as defined in claim 12 wherein the width of said opening inthe circumferential direction of the whirl chamber is at least threetimes as great as the intervals between the gas passages in the membranewall, and the gas passages are directed to emit gas jets inclined atangles less than 35 to the surface of the membrane wall.

14. A device as defined in claim 12 wherein:

(a) the surface of the membrane wall which adjoins the passive part ofthe whirl chamber is directed upwardly and said membrane wall has alongitudinal dimension which is many times the width of said opening,

(b) said device includes a plurality of said passive chamber parts, eachbeing a trough-shaped housing and disposed transversely to thelongitudinal direction of the membrane wall, and

(c) said device includes conveying means for moving said housings inunison and continuously along a circuit that includes:

(1) an upper course in which the said openings are upward and thehousings move in spaced relation above the membrane wall oppositely tosaid lon- 7 gitudinal direction, and

(2) a lower course in which said housings are inverted, with theiropenings juxtaposed to said membrane wall, and move in the saidlongitudinal direction.

15. A device as defined in claim 14 wherein:

(a) said upwardly directed surface of the membrane wall is substantiallyflat,

(b) each of said housings has at each end thereof a closure closing atleast an area which is adjacent to the confining wall,

said inlet means includes a feeder positioned to supply said material bygravity into the housings through the said openings thereof while therespective housing is in said upper course, and

(d) said outlet means includes a receiver situated beyond the end of themembrane wall toward which the housings move in the lower course forreceiving said material.

16. A device as defined in claim 14 wherein said outlet means includesan opening formed at an end of each housing at a location displacedradially inwards from the confining wall thereof for the outflow of gas.

17. A device as defined in claim 14 wherein said outlet means includespassages formed in the confining wall of each housing for the outflow ofgas.

18. A device as defined in claim 7 wherein said membrane wall is curvedconcavely toward the interior of the whirl chamber and is a stationarypart of the chamber.

19. A device as defined in claim 18 wherein said whirl chamber iselongated along a central axis of concavity, the confining wall thereof"being defined only in part by said membrane wall which extends throughan are between about 20 and about said central axis, and the remainingpart of said confining wall is imperforate save for said inlet andoutlet means when any of the latter is formed in said confining wall.

20. A device as defined in claim 18 wherein:

(a) said whirl chamber is substantially cylindrical and is mounted withthe central axis thereof substantially horizontal,

(b) said whirl chamber has end walls closing at least the area adjacentto the confining wall,

(c) said inlet means includes an inlet opening formed in said confiningwall at a level above the lowest part thereof near one axial end of thechamber, and

(d) said outlet means includes an outlet opening for said materialformed in said confining wall and dis placed in the axial direction fromsaid inlet opening.

21. A device as defined in claim 20 wherein at least one 13 14 of saidend walls of the whirl chamber has an opening 2,044,370 6/1936 Shodron34-225 XR formed therein at a location spaced radially inwards from2,044,744 6/ 1936 Hansen 34-10 XR the confining wall. 2,456,674 12/ 1948Caughey 3457 22. A device as defined in claim 20 which includes means2,461,134 2/ 1949 Arnold 3457 for varying the inclination of saidcentral axis of the whirl 5 2,501,487 3/ 1950 Whitman 3457 chamber,whereby the residence time of said material with- 3,267,585 8/ 1966Futer 34236 in the whirl chamber can be adjusted. 3,276,627 10/ 1966Birkestrand 34-136 References Cited FREDERICK L. MATTESON, JR., PrimaryExaminer.

UNITED STATES PATENTS 10 H. B. RAMEY, Assistant Examiner.

1,802,960 4/1931 Simonds 26321 US. Cl. X.R.

2,020,960 11/1935 Pehrson et al. 34135 3457, 236

